Ultrasonic transducers preferably include small but precisely dimensioned piezoelectric blocks in order to provide a high degree of part-to-part repeatability with low material costs. Conventional devices generally include a cylindrical piezoelectric block having a thickness that defines a resonant frequency of the piezoelectric block. In these devices, the element thickness may be, for example, about 7.0 mm when operated at 170 kHz and about 3.0 mm when operated at 400 kHz. However, fabricating precisely dimensioned piezoelectric cylinders of this size and shape can be very expensive as the cylinder faces have to be machined after firing.
Furthermore, conventional devices generally provide an electrical connection to the piezoelectric block using a soldered wire. However, solder can be unreliable and may cause increased part-to-part variability as the mass and placement of solder is not tightly controlled and can have a significant effect on the transducer vibrational behavior. As the size of the piezoelectric block decreases, these problems generally become more severe.